81 research outputs found

    Hadron masses in cavity quantum chromodynamics to order αs2\alpha_s^2

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    The non-divergent diagrams describing two-gluon exchange and annihilation between quarks and antiquarks are calculated in the Feynman gauge, based on quantum chromodynamics in a spherical cavity. Using the experimental NN, Δ\Delta, Ω\Omega, and ρ\rho masses to fit the free parameters of the M.I.T.\ bag model, the predicted states agree very well with the observed low-lying hadrons. As expected, the two-gluon annihilation graphs lift the degeneracy of the π\pi and η\eta, while the ρ\rho and ω\omega remain degenerate. Diagonalizing the ηη\eta - \eta' subspace Hamiltonian yields a very good value for the mass of the η\eta meson.Comment: 15 pages, 2 figure

    The anomalous magnetic moment of baryons in cavity QCD

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    Bibliography: pages 86-87.Using a generalised form of the Gell-Mann and Low theorem, all the diagrams in cavity QCD to order as that contribute to the magnetic moment are calculated. The calculations are performed for massive quarks so a mass renormalisation scheme has been developed to cope with the new divergences this brings into the self-energy insert diagrams. The results of this work show that no improvement on the simple SU(3) model is made by including these corrections. These calculations point to a smaller value of αs than that which is usually used

    Gauging the Shadow Sector with SO(3)

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    We examine the phenomenology of a low-energy extension of the Standard Model, based on the gauge group SU(3) x SU(2) x U(1) x SO(3), with SO(3) operating in the shadow sector. This model offers νeνs\nu_{e} \to \nu_{s} and νμντ\nu_{\mu} \to \nu_{\tau} oscillations as the solution of the solar and atmospheric neutrino problems. Moreover, it provides a neutral heavy shadow lepton X that could play the role of a cold dark matter particle.Comment: 8 page

    Nonlinear evolution of dark matter and dark energy in the Chaplygin-gas cosmology

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    The hypothesis that dark matter and dark energy are unified through the Chaplygin gas is reexamined. Using generalizations of the spherical model which incorporate effects of the acoustic horizon we show that an initially perturbative Chaplygin gas evolves into a mixed system containing cold dark matter-like gravitational condensate.Comment: 11 pages, 3 figures, substantial revision, title changed, content changed, added references, to appear in JCA

    Meson-meson scattering within one loop Chiral Perturbation Theory and its unitarization

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    We present the complete one-loop calculation of all the two meson scattering amplitudes within the framework of SU(3) Chiral Perturbation Theory, which includes pions, kaons and the eta. In addition, we have unitarized these amplitudes with the coupled channel Inverse Amplitude Method, which ensures simultaneously the good low energy properties of Chiral Perturbation Theory and unitarity. We show how this method provides a remarkable description of meson-meson scattering data up to 1.2 GeV including the scattering lengths and the generation of seven light resonances, which is consistent with previous determination of the chiral parameters. Particular attention is paid to discuss the differences and similarities of this work with previous analysis in the literature.Comment: 20 pages, 5 figures. Comments on sigma, kappa and eta', as well as some references added. Final version to appear in Phys.Rev.

    Business Ethics: The Promise of Neuroscience

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    Recent advances in cognitive neuroscience research portend well for furthering understanding of many of the fundamental questions in the field of business ethics, both normative and empirical. This article provides an overview of neuroscience methodology and brain structures, and explores the areas in which neuroscience research has contributed findings of value to business ethics, as well as suggesting areas for future research. Neuroscience research is especially capable of providing insight into individual reactions to ethical issues, while also raising challenging normative questions about the nature of moral responsibility, autonomy, intent, and free will. This article also provides a brief summary of the papers included in this special issue, attesting to the richness of scholarly inquiry linking neuroscience and business ethics. We conclude that neuroscience offers considerable promise to the field of business ethics, but we caution against overpromise

    Critical Essay: Organizational cognitive neuroscience drives theoretical progress, or: The curious case of the straw man murder:organizational cognitive neuroscience drives theoretical progress, or: The curious case of the straw man murder

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    In this critical essay, we respond to Lindebaum’s (2016) argument that neuroscientific methodologies and data have been accepted prematurely in proposing novel management theory. We acknowledge that building new management theories requires firm foundations. We also find his distinction between demand and supply side forces helpful as an analytical framework identifying the momentum for the contemporary production of management theory. Nevertheless, some of the arguments Lindebaum (2016) puts forward, on closer inspection, can be contested, especially those related to the supply side of organizational cognitive neuroscience (OCN) research: fMRI data, motherhood statements and ethical concerns. We put forward a more positive case for OCN methodologies and data, as well as clarifying exactly what OCN really means, and its consequences for the development of strong management theory

    Impact of cross-section uncertainties on supernova neutrino spectral parameter fitting in the Deep Underground Neutrino Experiment

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    A primary goal of the upcoming Deep Underground Neutrino Experiment (DUNE) is to measure the O(10)\mathcal{O}(10) MeV neutrinos produced by a Galactic core-collapse supernova if one should occur during the lifetime of the experiment. The liquid-argon-based detectors planned for DUNE are expected to be uniquely sensitive to the νe\nu_e component of the supernova flux, enabling a wide variety of physics and astrophysics measurements. A key requirement for a correct interpretation of these measurements is a good understanding of the energy-dependent total cross section σ(Eν)\sigma(E_\nu) for charged-current νe\nu_e absorption on argon. In the context of a simulated extraction of supernova νe\nu_e spectral parameters from a toy analysis, we investigate the impact of σ(Eν)\sigma(E_\nu) modeling uncertainties on DUNE's supernova neutrino physics sensitivity for the first time. We find that the currently large theoretical uncertainties on σ(Eν)\sigma(E_\nu) must be substantially reduced before the νe\nu_e flux parameters can be extracted reliably: in the absence of external constraints, a measurement of the integrated neutrino luminosity with less than 10\% bias with DUNE requires σ(Eν)\sigma(E_\nu) to be known to about 5%. The neutrino spectral shape parameters can be known to better than 10% for a 20% uncertainty on the cross-section scale, although they will be sensitive to uncertainties on the shape of σ(Eν)\sigma(E_\nu). A direct measurement of low-energy νe\nu_e-argon scattering would be invaluable for improving the theoretical precision to the needed level.Comment: 25 pages, 21 figure
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